The present invention relates to a method and device for determining an interconnect route in a circuit board from a plurality of virtual interconnect targets to lands which are arranged in a matrix around the virtual interconnect targets, and also relates to an information storage medium.
A bare tip mounting is ideal for pursuing miniaturization of semiconductor devices. However, because bare-chip mounting results in difficulty in assuring quality and in handling, the semiconductor device is processed into a package form to deal with this problem. As a package form meeting the requirements, particularly, for multi-terminal arrangement, a BGA (Ball Grid Array) package has been developed in recent years.
A flexible circuit board is used as one BGA type package. Such a circuit board is provided with a lead group connected to an IC terminal group, and a ball land group are arranged in a matrix around the lead group. Each land is provided with a solder ball, as required. This circuit board mounted with an IC is surface-mounted on a motherboard or the like through the solder balls.
An important subject in using such a circuit board is how to determine interconnect routes between each lead (a virtual interconnect target) in the lead group and each land ball in the land group arranged around the lead group.
In particular, circuit boards recently used have many leads and land balls provided on a circuit board for mounting ICs due to the increased number of terminals of the ICs to be mounted. Accordingly, how efficiently the interconnect routes are designed from each lead to each ball land without intersecting the interconnect route becomes important for shortening the development period and reducing the cost of a circuit board.
However, in a conventional technique, a designer determines interconnect routes between each lead and each land manually on a drawing by trial and error. Because such a design work requires time and labor, it was impossible to design a circuit board in a short time at a low cost.
Specifically, the amount of interconnect which can pass through a space between each of the lands differs depending on various parameters such as spaces between ball lands and widths of interconnect leads used. Therefore, it is necessary that the interconnect route should be determined so that the amount of interconnect between the lands may not exceed the allowable amount and also that the interconnects may not intersect each other.
However, if a land which cannot be interconnected should be found during a design work using a conventional technique in which a designer determines the interconnect routes between each lead and each land manually on a drawing by trial and error, the determination of the interconnect routes has to be repeated from the beginning by changing the parameters. Thus, the design work must be dependent on the experience and intuition of the designer.
The present invention has been made in view of the above-described conventional problems. An object of the present invention is to provide a method, device, and information storage medium for determining interconnect routes in a circuit board between virtual interconnect target group and lands which are arranged in at least one of inside and outside of the column, efficiently in a short period of time.
(1) To achieve the above object, the present invention provides a method of determining interconnect routes in a circuit board, the interconnect routes running from a plurality of virtual interconnect targets to lands arranged in a matrix on at least one of inside and outside of the virtual interconnect target, the virtual interconnect target forming a target group arranged into a substantially rectangular frame, the method comprising:
a first step of assigning an order of priority to each of the lands; and
a second step of performing processing for determining an interconnect route between a next virtual interconnect target adjacent to another virtual interconnect target of which an interconnect route has been determined and a next interconnect land according to the order of priority,
wherein, in the first step, when a rectangle formed by the lands is divided into eight areas by centerlines and diagonals, and when a plurality of oblique lines connecting lands included in the lands which are adjoining each other in a direction parallel to the diagonals are priority order setting lines,
priority of each land included in each of the divided areas is set so that higher priority is assigned to a land on one of the priority order setting lines further from the diagonals, and higher priority is assigned to a land positioned further from the target group, on the same priority order setting line.
The present invention also provides a program for performing the above-mentioned method of determining an interconnect route.
The present invention further provides a computer readable information storage medium which stores information (for example, a program) for determining interconnect routes in a circuit board, the interconnect routes running from a plurality of virtual interconnect targets to lands arranged in a matrix on at least one of inside and outside of the virtual interconnect target, the virtual interconnect target forming a target group arranged into a substantially rectangular frame,
the information comprising:
a first information (for example, a program) for assigning an order of priority to each of the lands; and
a second information (for example, a program) for performing processing for determining an interconnect route between a next virtual interconnect target adjacent to another virtual interconnect target of which an interconnect route has been determined and a next interconnect land according to the order of priority,
wherein the first information comprises information (for example, a program) for setting priority of each land included in each of the divided areas, when a rectangle formed by the lands is divided into eight areas by centerlines and diagonals, and when a plurality of oblique lines connecting lands included in the lands which are adjoining each other in a direction parallel to the diagonals are priority order setting lines,
so that higher priority is assigned to a land on one of the priority order setting lines further from the diagonals, and higher priority is assigned to a land positioned further from the target group, on the same priority order setting line.
According to the present invention, a land which should be the interconnect land can be automatically determined based on the order of priority assigned to each land. Therefore, the interconnect routes can be determined efficiently and certainly.
When there is no other restriction, the order of priority means an order by which a land with a higher priority is selected as the interconnect land.
In the present invention, an interconnect route to lands arranged in a matrix on at least either inside or outside of the target group can be determined.
In the case where the interconnect routes for outer lands positioned outside the target group are determined,
it is preferable that, in the second step, a number of interconnect routes being able to pass through a space between adjoining lands is previously set to a certain value and
when the number of determined interconnect routes has reached the set value in the space between the adjoining lands, the processing for determining an interconnect route is performed to a next interconnect land that is an unconnected land and is one of the lands forming the space in which the number of the interconnects has reached the set value, instead of using the order of priority.
In addition, in the case where the interconnect routes for outer lands positioned outside the target group are determined,
the second information preferably comprise information for:
previously setting a number of interconnect routes being able to pass through a space between adjoining lands to a certain value, and
when the number of determined interconnect routes has reached the set value in the space between the adjoining lands, performing the processing for determining an interconnect route to a next interconnect land that is an unconnected land and is one of the lands forming the space in which the number of the interconnects has reached the set value, instead of using the order of priority.
The above constitution ensures more certain determination of a land which should be the next interconnect land for the outside land group locating outside the target group.
Therefore, the interconnect routes can be determined more efficiently and certainly.
(2) The present invention further provides a method of determining interconnect routes in a circuit board, the interconnect routes running from a plurality of virtual interconnect targets to lands arranged in a matrix on at least one of inside and outside of the virtual interconnect target, the virtual interconnect target forming a target group arranged into a substantially rectangular frame, the method comprising:
a step of virtually placing a plurality of counters between each of the lands arranged in a matrix, the counters being opened by a specified rule and counting the number of interconnect routes passing through a space between adjoining lands;
an interconnect route determination step in which processing for determining an interconnect route is repeatedly performed, the processing for determining an interconnect route between a next virtual interconnect target adjacent to another virtual interconnect target of which an interconnect route has been determined and a next interconnect land which is selected by a specified rule, so that an interconnect, running through a space between lands in which an open counter exists, passes without intersecting with an interconnect route which has already been determined; and
a counter control step in which, when count value of an open counter has reached a set amount, the open counter is closed and another counter associated with the open counter is opened or closed according to a specified rule, so as to set a route for leading a new interconnect.
The present invention also provides a program for performing the method of interconnect route determination.
The present invention further provides a computer readable information storage medium which stores an information (for example, a program) for determining interconnect routes in a circuit board, the interconnect routes running from a plurality of virtual interconnect targets to lands arranged in a matrix on at least one of inside and outside of the virtual interconnect target, the virtual interconnect target forming a target group arranged into a substantially rectangular frame, the information comprising:
information (for example, a program) for virtually placing a plurality of counters between each of the lands arranged in a matrix, the counters being opened by a specified rule and counting the number of interconnect routes passing through a space between adjoining lands;
information (for example, a program) for determining an interconnect route in which processing for determining an interconnect route is repeatedly performed, the processing for determining an interconnect route between a next virtual interconnect target adjacent to another virtual interconnect target of which an interconnect route has been determined and a next interconnect land which is selected by a specified rule, so that an interconnect, running through a space between lands in which an open counter exists, passes without intersecting with an interconnect route which has already been determined; and
information (for example, a program) for counter control which, when count value of an open counter has reached a set amount, closes the open counter and opens or closes another counter associated with the open counter according to a specified rule, so as to set a route for leading a new interconnect.
According to the present invention, a plurality of counters which count the number of leads passing through the areas between the adjoining lands are virtually arranged around each land which is arranged in a matrix. For example, giving attention to one land, there are at least four lands arranged in a matrix around that particular land. In this instance, four counters are virtually arranged between this land and adjoining lands. These counters are opened according to a specified rule.
The interconnect route between each target and each land is determined so that the interconnect passes through the spaces between the lands where open counters exist without intersecting the previously determined interconnect routes.
When an interconnect route passes through the spaces between the lands, the open counter performs the counting operation. When the number of interconnect routes which pass through the spaces between the lands reaches the predetermined reference number, i.e., typically the number of interconnect routes capable of providing interconnect between the lands, the count value of the counter is judged to reach the maximum (i.e., judged to be impossible to route any further), the open counter is closed.
By repeating such determinations for the interconnect routes and counter control, the interconnect routes between the target group and land group can be determined automatically so that an allowable number of interconnect routes may pass between each land without intersection of the interconnect routes.
In particular, according to the present invention, the automatic interconnect between the target leads and lands can be efficiently performed in a short time based on the count data of the counters virtually placed around each land arranged in a matrix.
In this application, the corresponding land means, for example, the lands adjacent to the target lead side, when viewed from the counter to be closed, or the lands positioned in the direction of deciding the subsequent interconnect route, when viewed from the interconnect routes already determined.
In the present invention, an interconnect route to lands arranged in a matrix on at least either inside or outside the target group can be automatically determined.
In the case where the interconnect routes for outer lands positioned outside the target group are determined,
in the counter control step, it is preferable that opening and closing conditions of the virtual counter are initially set according to a specified rule, and
when a count value of an open counter has reached the set amount, the open counter is closed and another open counter of which an interconnect route to an assigned land thereof has been determined is also closed, then closed counters which are positioned on the opposite side of the open counters to be closed interposing assigned lands therebetween are opened, thereby setting a route for leading a new interconnect.
In addition, in the case where the interconnect routes for outer lands positioned outside the target group are determined, the information for counter control preferably comprise information for:
initially setting opening and closing conditions of the virtual counter according to a specified rule, and
when a count value of an open counter has reached the set amount, closing the open counter and another open counter of which interconnect route to an assigned land thereof has been determined, then opening closed counters which are positioned on the opposite side of the open counters to be closed interposing assigned lands therebetween, thereby setting a route for leading a new interconnect.
By adopting such a constitution, the interconnect route to an outside land group which is located outside the target group can be determined automatically and efficiently.
The following constitution can be adopted to determine the interconnect route for an inner land group which is located inside the target group.
Specifically, in the case where the interconnect routes for inner lands positioned inside the target group are determined, in the counter control step, it is preferable that opening and closing conditions of the virtually placed counter are initially set according to a specified rule, and
when a count value of an open counter has reached the set amount, the open counter is closed, and other open counters on a centerline side and a target group side of a starting land of an interconnect, running through a space between lands in which the open counter is located are closed, is also closed, thereby setting a route for leading a new interconnect.
In addition, in the case where the interconnect routes for inner lands positioned inside the target group are determined, the information for counter control preferably comprise information for:
initially setting opening and closing conditions of the virtually placed counter according to a specified rule, and
when a count value of an open counter has reached the set amount, closing the open counter and other open counters on a centerline side and a target group side of a starting land of an interconnect which runs through a space between lands in which the open counter is located, thereby setting a route for leading a new interconnect.
The above constitution ensures more certain determination of a land which should be the next interconnect land for the inside land group locating inside the target group.
(3) In the case where the interconnect routes for outer lands positioned outside the target group are determined,
in the interconnect route determination step, it is preferable that each of interconnect routes from lands arranged in a matrix to plating leads disposed in the outer periphery of the lands is determined so that an interconnect, running through a space between lands in which an open counter exists, passes without intersecting with an interconnect route which has already been determined, and
wherein, in the counter control step, when a count value of an open counter has reached the set amount due to the processing for determining an interconnect route between the plating leads and the lands, the open counter is closed, then a closed counter which is positioned on the opposite side of the open counter to be closed interposing an assigned land therebetween is opened, thereby setting a route for leading a new interconnect.
In the case where the interconnect routes for outer lands positioned outside the target group are determined,
the information for determining an interconnect route preferably comprise information for determining each of interconnect routes from lands arranged in a matrix to plating leads disposed in the outer periphery of the lands so that an interconnect, running through a space between lands in which an open counter exists, passes without intersecting with an interconnect route which has already been determined, and
wherein the information for counter control comprises information for,
when a count value of an open counter has reached the set amount due to the processing for determining an interconnect route between the plating leads and the lands,
closing the open counter, then opening a closed counter which is positioned on the opposite side of the open counter to be closed interposing an assigned land therebetween, thereby setting a route for leading a new interconnect.
This allows the interconnect routes between the lands and the plating leads, as well as the interconnect routes between the inner leads and the lands, to be determined automatically and efficiently.
(4) In addition, it is preferable in the present invention that an order of priority is previously assigned to each of the lands arranged in a matrix, and
wherein the interconnect route determination step comprises:
a third step of determining a next interconnect land based on the order of priority of each of the lands and a presence or absence of the open counter; and
a fourth step of performing processing for determining an interconnect route between the determined interconnect land and a virtual interconnect target based on a position of the open counter.
In addition, it is preferable in the information medium of the present invention that an order of priority is previously assigned to each of the lands arranged in a matrix, and
wherein the information for determining an interconnect route comprises:
a third information for determining a next interconnect land based on the order of priority of each of the lands and a presence or absence of the open counter; and
a fourth information for performing processing for determining an interconnect route between the determined interconnect land and a virtual interconnect target based on a position of the open counter.
Specifically, in the present invention, when one interconnect route is determined, a subsequent interconnect land is determined based on the order of priority previously assigned to each land and the positions at which counters are opened as the count value has reaches the maximum owing to immediately preceding interconnect route determination. The interconnect route between the determined interconnect land and a target interconnect route is determined based on the position in which an open counter exists.
In this manner, the subsequent interconnect land can be decided automatically in the present invention based on the order of priority assigned to each land and the occurrence of open counters of which count value has reached the set value. Therefore, the interconnect routes can be determined more efficiently and certainly.
When there is no other restriction, the order of priority means an order by which a land with a higher priority is selected as the interconnect land.
(5) Further, in the present invention the order of priority of each land arranged in a matrix is preferably determined that,
when a rectangle formed by the lands arranged in a matrix is divided into eight areas by centerlines and diagonals, and when a plurality of oblique lines connecting lands included in the lands which are adjoining each other in a direction parallel to the diagonals are priority order setting lines,
priority of each land included in each of the divided areas is set so that higher priority is assigned to a land on one of the priority order setting lines further from the diagonals, and higher priority is assigned to a land positioned further from the target group, on the same priority order setting line.
This causes the interconnect lands to be selected one after another from the lands which are positioned remote from the target when viewed from the entire interconnect route, so that shortest interconnect routes between each lead and land can be determined, when viewed from the entire circuit.
In the case where the interconnect routes for inner lands positioned inside the target group are determined, it is preferable to adopt following constitution.
Specifically, when a plurality of oblique lines connecting lands included in the inner lands which are adjoining each other in a oblique direction intersecting with each of priority order setting lines are intersecting lines, an interconnect proceeding point is virtually positioned at each position where a plurality of intersecting lines and the plurality of priority order setting lines intersect each other.
Then the third step further comprises:
a step of setting an order of priority among four interconnect proceeding points around an interconnect land, in the order of a first point on the target group side and the centerline side, and a second point on the target group side and the diagonal side, determining an interconnect drawing route from the interconnect land toward a point having higher priority on condition that an interconnect route exists, and, when an interconnect drawing route to the second point has been determined, closing a virtual counter on the target group side and the centerline side of the interconnect land; and
a step of setting the order of priority for determining an interconnect route from an interconnect proceeding point selected as an interconnect route to a next interconnect proceeding point adjoining to the selected interconnect proceeding point, in the order of the target group side and the diagonal side, and determining an interconnect route toward a point positioned in a direction having higher priority, on condition that a virtual counter positioned on a route toward the next point is open.
Furthermore, the third information which performs the process of interconnect route determination may comprises:
information for setting an order of priority among four interconnect proceeding points around an interconnect land, in the order of a first point on the target group side and the centerline side, and a second point on the target group side and the diagonal side, determining an interconnect drawing route from the interconnect land toward a point having higher priority on condition that an interconnect route exists, and, when an interconnect drawing route to the second point has been determined, closing a virtual counter on the target group side and the centerline side of the interconnect land; and
information for setting the order of priority for determining an interconnect route from an interconnect proceeding point selected as an interconnect route to a next interconnect proceeding point adjoining to the selected interconnect proceeding point, in the order of the target group side and the diagonal side, and determining an interconnect route toward a point positioned in a direction having higher priority, on condition that the a virtual counter positioned on a route toward the next point is open.
(6) In addition, the method of the present invention preferably include a step of inputting an interconnect parameter,
wherein, in the interconnect route determination step, the processing for determining an interconnect route is performed based on the inputted parameter.
The present invention also provides a program for performing the above method.
The information storage medium of the present invention preferably include information (for example, a program) for inputting an interconnect parameter,
wherein the information for determining an interconnect route comprises information for performing the processing for determining an interconnect route based on the inputted parameter.
The device for determining interconnect routes of the present invention preferably comprise:
means for inputting an interconnect parameter, and
means for determining an interconnect route between a virtual interconnect target group arranged in a rectangular shape and at least one of a land group rectangularly arranged around outside the virtual interconnect target group and a rectangular land group arranged inside the virtual interconnect target group, by using any one of the methods described above.
The information storage medium of the present invention preferably store a program for performing:
means for inputting an interconnect parameter, and
means for determining an interconnect route between a virtual interconnect target group arranged in a rectangular shape and at least one of a land group rectangularly arranged around outside the virtual interconnect target group and a rectangular land group arranged inside the virtual interconnect target group, by using any one of the methods described above.
According to the present invention, if parameters for interconnect are input, a process for determining the interconnect routes between the above-described interconnect lands is performed based on the inputted parameters.
Therefore, when it is judged that the routing can not be performed with the parameters entered, new parameters may be entered.
Optimal parameters which enables routing between the target group and land group can be input in this manner, so that the optimal circuit conditions for manufacturing circuit boards can be determined prior to manufacturing the circuit boards.
In this case, as the parameters described above, items such as the following may be selectively used, for example, sizes of the land group arranged in a matrix, number of cells (number of lands) constituting the matrix, sizes of each land, sizes of land gaps (sizes of non-interconnect area residing around the lands), width of each interconnect pattern, and gaps between leads which are distances between the interconnect patterns.
(7) The semiconductor device of the present invention comprises the interconnect route which is determined using at least one of the above-described method, device, and information stored in the information storage medium.